Grade rods (sometimes referred to as measuring sticks or surveyor's rods) are typically used by surveyors, civil engineers, or construction workers to measure elevations or vertical distances at a job site. Conventional grade rods typically have visual measurement markers (numbers and associated standardized markings) printed directly on the exterior of the rod or on tape (for example, a band or strip) associated with the exterior of the rod. Thus, a conventional grade rod operates much like an ordinary ruler or measuring tape. Depending on the particular application for which the grade rod is used, the unit of measure indicated by the grade rod may vary. For example, the measurement provided by a grade rod may be in imperial units (for example, feet, inches, and fractions of an inch), metric units (for example, meters and centimeters), or derivations thereof (for example, feet, tenths of feet, and hundredths of feet). Further, the distance being measured by a grade rod may have a variety of formats. For example, the measurement being made with a grade rod may be the true elevation of a point from sea level, the elevation above or below a known reference elevation, or the elevation of a point above or below a “zero” point on the grade rod (sometimes referred to as the cut-and-fill value).
A laser detector and laser light source are typically used in connection with a grade rod in order to provide accurate measurements relative to a reference plane. For example, the laser light source (such as a rotating laser light source) can emit a plane of light that defines a reference plane at a known elevation. Depending on the application, the reference plane may be level or sloping. A laser detector that is coupled to the grade rod and that is configured to be moved up and down the grade rod can provide an indication (such as an audible and/or visual signal, which is sometimes referred to herein as the “on-grade signal”) when the reference plane is incident with a particular point of the laser detector.
In conventional operation, the base of the grade rod is placed at a known elevation (for example, a finish floor or sub grade). The laser detector is then positioned on the grade rod (for example, moved upwards or downwards along the rod) so that the “on-grade” signal is emitted or displayed. The operator then notes the elevation on the grade rod where the “on-grade” signal occurred. This measurement represents the base value or reference elevation. The grade rod is then moved to another location, and the process repeated until the “on-grade” signal is emitted or displayed on the laser detector. The difference between the location of the laser detector on the grade rod at the new location and the reference elevation is then calculated to determine whether the new location is too high or too low relative to the desired elevation and by how much. With conventional survey systems, this calculation is performed manually. The manual calculation of these grade values can be tedious, time-consuming, and prone to error. Accordingly, improved surveying systems that reduce the amount of manual computation while maintaining or improving accuracy are desired.